Radio frequency module and communication device

ABSTRACT

A radio frequency module includes: a module board including a first principal surface and a second principal surface; a first power amplifier; a second power amplifier; a first output transformer connected to the first power amplifier; and a second output transformer connected to the second power amplifier. The first power amplifier and the second power amplifier are disposed on the first principal surface. The first output transformer and the second output transformer are disposed inside the module board or on the second principal surface.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims priority to Japanese Patent Application No. 2020-076285 filed on Apr. 22, 2020. The entire disclosure of the above-identified application, including the specification, drawings and claims is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a radio frequency (RF) module and a communication device.

BACKGROUND

Mobile communication devices such as mobile phones include a power amplifier that amplifies a radio frequency transmission signal.

Japanese Unexamined Patent Application Publication No. 2010-118916 discloses a differential power amplifier that includes: a first transistor which receives an input of a non-inverted input signal; a second transistor which receives an input of an inverted input signal; and a transformer disposed on the output terminal side of the first transistor and the second transistor. The transformer includes magnetically-coupled two primary coils and one secondary coil. The two primary coils are connected to each other in parallel, and each magnetically coupled to the secondary coil, allowing the input impedance of the primary coils to be reduced without decreasing Q-factors. As a result, it is possible to improve power gain.

SUMMARY Technical Problems

However, as recognized by the present inventor, when the differential power amplifier disclosed by Japanese Unexamined Patent Application Publication No. 2010-118916 is applied to a radio frequency front-end circuit that supports multi-band technologies, differential power amplifiers need to be provided for the respective communication bands, leading to an increase in the total number of power amplifiers arranged. Furthermore, the differential power amplifier includes a large number of circuit elements, and thus there arises a problem that the radio frequency module increases in size.

The present disclosure addresses the above-described problems, and is presented to provide a small-sized radio frequency module that includes a differential power amplifier and supports multi-band technologies, and a communication device including the radio frequency module.

Solutions

In order to provide such a radio frequency module and such a communication device as described above, a radio frequency module according to one aspect of the present disclosure includes a module board including a first principal surface and a second principal surface on opposite sides of the module board; a first power amplifier configured to amplify a transmission signal of a first frequency band; a second power amplifier configured to amplify a transmission signal of a second frequency band different from the first frequency band; a first output transformer including a first coil and a second coil; and a second output transformer including a third coil and a fourth coil. In this radio frequency module, the first power amplifier includes a first amplifying element and a second amplifying element, the second power amplifier includes a third amplifying element and a fourth amplifying element, one of ends of the first coil is connected to an output terminal of the first amplifying element, a remaining one of the ends of the first coil is connected to an output terminal of the second amplifying element, and one of ends of the second coil is connected to an output terminal of the first power amplifier, one of ends of the third coil is connected to an output terminal of the third amplifying element, a remaining one of the ends of the third coil is connected to an output terminal of the fourth amplifying element, and one of ends of the fourth coil is connected to an output terminal of the second power amplifier, the first power amplifier and the second power amplifier are disposed on the first principal surface, and the first output transformer and the second output transformer are disposed inside the module board or on the second principal surface.

Advantageous Effects

According to the present disclosure, a small-sized radio frequency module that includes a differential power amplifier and supports multi-band technologies, and a communication device including the radio frequency module are provided.

BRIEF DESCRIPTION OF DRAWINGS

These and other advantages and features will become apparent from the following description thereof taken in conjunction with the accompanying Drawings, by way of non-limiting examples of embodiments disclosed herein.

FIG. 1 is a diagram illustrating a circuit configuration of a radio frequency module (or RF front-end circuitry) and a communication device according to an embodiment.

FIG. 2 is a diagram illustrating a circuit configuration of a transmission amplifier circuit.

FIG. 3A is a schematic diagram illustrating a plan view configuration of a radio frequency module according to Working Example 1.

FIG. 3B is a schematic diagram illustrating a cross-sectional configuration of the radio frequency module according to Working Example 1.

FIG. 4A is a schematic diagram illustrating a plan view configuration of a first principal surface of a radio frequency module according to Variation 1.

FIG. 4B is a schematic diagram illustrating a plan view configuration of a first principal surface of a radio frequency module according to Variation 2.

FIG. 5 is a schematic diagram illustrating a cross-sectional configuration of a radio frequency module according to Variation 3.

FIG. 6A is a schematic diagram illustrating a plan view configuration of a radio frequency module according to Working Example 2.

FIG. 6B is a schematic diagram illustrating a cross-sectional configuration of the radio frequency module according to Working Example 2.

DESCRIPTION OF EMBODIMENTS

The following describes in detail embodiments of the present disclosure. Each of the embodiments described below illustrates a general or specific example. The numerical values, shapes, materials, structural components, the arrangement and connection of the structural components, and so on, illustrated in the following embodiments are mere examples, and therefore do not limit the present disclosure. Among the structural components in the following working examples and variations, structural components not recited in the independent claims are described as arbitrary structural components. In addition, the sizes of structural components and the ratios of the sizes in the drawings are not necessarily strictly illustrated. In each of the diagrams, substantially the same structural components are denoted by the same reference signs, and redundant description may be omitted or simplified.

In addition, in the following description, terms indicating relationships between components such as parallel and vertical and terms indicating the shapes of components such as a quadrilateral shape, and numerical ranges do not represent only the strict meanings but include also a substantially equivalent range, such as a difference of approximately several percent.

In addition, in the following description, in an example of A, B, and C being mounted on a board, “in a plan view of the board (or the principal surface of the board), C is disposed between A and B” means that at least one of a plurality of line segments connecting arbitrary points in A and arbitrary points in B passes through a region in C in a plan view of the board. Furthermore, a plan view of the board means that the board and circuit elements mounted on the board are orthographically projected on a plane parallel to the principal surface of the board.

In addition, in the following description, a “transmission path” refers to a transfer path including: a line along which a radio frequency transmission signal propagates; an electrode directly connected to the line; a terminal directly connected to the line or the electrode; and the like. Furthermore, a “reception path” refers to a transfer path including: a line along which a radio frequency reception signal propagates; an electrode directly connected to the line; a terminal directly connected to the line or the electrode; and the like. Furthermore, a “transmission and reception path” refers to a transfer path including: a line along which a radio frequency transmission signal and a radio frequency reception signal propagate; an electrode directly connected to the line; a terminal directly connected to the line or the electrode; and the like.

Embodiment 1. Circuit Configuration of Radio Frequency Module 1 and Communication Device 5

FIG. 1 is a diagram illustrating a circuit configuration of radio frequency module 1 and communication device 5 according to an embodiment. As illustrated in this diagram, communication device 5 includes radio frequency module 1, antenna 2, RF signal processing circuit (RFIC) 3, and baseband signal processing circuit (BBIC) 4.

RFIC 3 is an RF signal processing circuit that processes a radio frequency signal to be transmitted by antenna 2 and processes a radio frequency signal received by antenna 2. More specifically, RFIC 3 performs signal processing, by down-conversion or the like, on a reception signal that has been input via the reception signal path of radio frequency module 1, and outputs the reception signal generated by the signal processing to BBIC 4. In addition, RFIC 3 performs signal processing, by up-conversion or the like, on a transmission signal that has been input from BBIC 4, and outputs the transmission signal generated by the signal processing to the transmission signal path of radio frequency module 1.

BBIC 4 is a circuit that performs signal processing using an intermediate frequency band having a lower frequency than a frequency band of a radio frequency signal that is transferred through radio frequency module 1. The signal processed by BBIC 4 is, for example, used as an image signal for image display or as a sound signal for telephone conversation via a speaker.

RFIC 3 also functions as a controller that controls the connection of switches 41, 42, 43, and 44 included in radio frequency module 1, based on a communication band (frequency band) used. Specifically, RFIC 3 controllably switches connection between switches 41 to 44 included in radio frequency module 1, by a control signal (not illustrated). More specifically, RFIC 3 outputs a digital control signal for controlling switches 41 to 44, to power amplifier (PA) control circuit 80. PA control circuit 80 of radio frequency module 1 outputs a digital control signal to switches 41 to 44 according to the digital control signal that has been input from RFIC 3, thereby controlling connection and disconnection of switches 41 to 44.

RFIC 3 also functions as a controller that controls the gains of transmission amplifier circuits 10 and 20 included by radio frequency module 1, and power supply voltage Vcc and bias voltage Vbias that are supplied to transmission amplifier circuits 10 and 20. More specifically, RFIC 3 outputs digital control signals to control signal terminal 140 of radio frequency module 1. PA control circuit 80 of radio frequency module 1 outputs a control signal, power supply voltage Vcc, or bias voltage Vbias to transmission amplifier circuits 10 and 20 according to the digital control signal that has been input via control signal terminal 140, thereby adjusting the gains of transmission amplifier circuits 10 and 20. It should be noted that a control signal terminal that receives, from RFIC 3, a digital control signal for controlling the gains of transmission amplifier circuits 10 and 20 may be different from a control signal terminal that receives, from RFIC 3, a digital control signal for controlling power supply voltage Vcc and bias voltage Vbias to be supplied to transmission amplifier circuits 10 and 20. In addition, the controller may be disposed outside RFIC 3, for example, in BBIC 4.

Antenna 2 is connected to antenna connection terminal 100 of radio frequency module 1, and emits a radio frequency signal that has been output from radio frequency module 1. In addition, antenna 2 receives a radio frequency signal from the outside, and outputs the received radio frequency signal to radio frequency module 1.

It should be noted that, in communication device 5 according to the present embodiment, antenna 2 and BBIC 4 are not indispensable components.

Next, a detailed configuration of radio frequency module 1 will be described.

As illustrated in FIG. 1, radio frequency module 1 includes: antenna connection terminal 100; transmission amplifier circuits 10 and 20; low noise amplifier 30; transmission filters 61T, 62T, and 63T; reception filters 61R, 62R, and 63R; PA control circuit 80; matching circuits (matching network (MN)) 51, 52, 53, and 54; and switches 41, 42, 43, and 44.

Antenna connection terminal 100 is a common antenna terminal connected to antenna 2.

Transmission amplifier circuit 10 is an amplifier circuit of a differential amplifier type that amplifies transmission signals of communication band A and communication band B that have been input through transmission input terminals 111 and 112. It should be noted that radio frequency module 1 may include, instead of transmission amplifier circuit 10, a first transmission amplifier circuit that amplifies a radio frequency signal of communication band A and a second transmission amplifier circuit that amplifies a radio frequency signal of communication band B.

Transmission amplifier circuit 20 is an amplifier circuit of a differential amplifier type that amplifies transmission signals of communication band C that have been input through transmission input terminals 121 and 122.

PA control circuit 80 adjusts the gains of amplifying elements included in transmission amplifier circuits 10 and 20, using a digital control signal input through control signal terminal 140. PA control circuit 80 may be implemented as a semiconductor integrated circuit (IC). The semiconductor IC is configured by, for example, a complementary metal oxide semiconductor (CMOS). More specifically, the semiconductor IC is fabricated by silicon on insulator (SOI) processing. This allows manufacturing the semiconductor IC at a low manufacturing cost. It should be noted that the semiconductor IC may include at least one of GaAs, SiGe, or GaN. With this, it is possible to output a radio frequency signal having a high-quality amplification performance and noise performance.

Low noise amplifier 30 is an amplifier that amplifies radio frequency signals of communication bands A, B, and C with low noise, and outputs the amplified radio frequency signals to reception output terminal 130. It should be noted that radio frequency module 1 may include a plurality of low noise amplifiers. For example, radio frequency module 1 may include a first low noise amplifier that amplifies radio frequency signals of communication bands A and B, and a second low noise amplifier that amplifies radio frequency signals of communication band C.

It should be noted that, in the present embodiment, communication bands A and B are lower in frequency than communication band C. Communication bands A and B are, for example, communication bands that belong to a middle band group (1.45 GHz to 2.2 GHz), and communication band C is, for example, a communication band that belongs to a high band group (2.3 GHz to 2.7 GHz). However, the high-low frequency relationship between communication band C and communication bands A and B is not limited to above-described example. Accordingly, communication bands A and B may be higher in frequency than communication band C. It should be noted that the middle band group is one example of the first frequency band, and communication band C is one example of the second frequency band different from the first frequency band.

Transmission filter 61T is disposed on transmission path AT that connects antenna connection terminal 100 and transmission input terminals 111 and 112, and passes a transmission signal in a transmission band of communication band A, among the transmission signals that have been amplified by transmission amplifier circuit 10. Transmission filter 62T is disposed on transmission path BT that connects antenna connection terminal 100 and transmission input terminals 111 and 112, and passes a transmission signal in a transmission band of communication band B, among the transmission signals that have been amplified by transmission amplifier circuit 10. Transmission filter 63T is disposed on transmission path CT that connects antenna connection terminal 100 and transmission input terminals 121 and 122, and passes a transmission signal in a transmission band of communication band C, among the transmission signals that have been amplified by transmission amplifier circuit 20.

Reception filter 61R is disposed on reception path AR that connects antenna connection terminal 100 and reception output terminal 130, and passes a reception signal in a reception band of communication band A, among the reception signals that have been input through antenna connection terminal 100. Reception filter 62R is disposed on reception path BR that connects antenna connection terminal 100 and reception output terminal 130, and passes a reception signal in a reception band of communication band B, among the reception signals that have been input through antenna connection terminal 100. Reception filter 63R is disposed on reception path CR that connects antenna connection terminal 100 and reception output terminal 130, and passes a reception signal in a reception band of communication band C, among the reception signals that have been input through antenna connection terminal 100.

Transmission filter 61T and reception filter 61R are included in duplexer 61 that has, as a passband, communication band A. Duplexer 61 transfers a transmission signal and a reception signal of communication band A in a frequency division duplex (FDD) system. Transmission filter 62T and reception filter 62R are included in duplexer 62 that has, as a passband, communication band B. Duplexer 62 transfers a transmission signal and a reception signal of communication band B in the FDD system. Transmission filter 63T and reception filter 63R are included in duplexer 63 that has, as a passband, communication band C. Duplexer 63 transfers a transmission signal and a reception signal of communication band C in the FDD system.

It should be noted that each of duplexers 61 to 63 may be a multiplexer including only a plurality of transmission filters, a multiplexer including only a plurality of reception filters, or a multiplexer including a plurality of duplexers. In addition, transmission filter 61T and reception filter 61R need not necessarily be included in duplexer 61. Transmission filter 61T and reception filter 61R may be a single filter that transfers a transmission signal and a reception signal of communication band A in a time division duplex (TDD) system. In this case, a switch for switching between transmission and reception is disposed on at least one of a preceding stage or a following stage of the above-described single filter. In the same manner as above, transmission filter 62T and reception filter 62R need not necessarily be included in duplexer 62. Transmission filter 62T and reception filter 62R may be a single filter that transfers a transmission signal and a reception signal of communication band B in the TDD system. In the same manner as above, transmission filter 63T and reception filter 63R need not necessarily be included in duplexer 63. Transmission filter 63T and reception filter 63R may be a single filter that transfers a transmission signal and a reception signal of communication band C in the TDD system.

Matching circuit 51 is disposed on a path that connects switch 44 and duplexer 61, and matches the impedance of switch 44 and antenna 2 with the impedance of duplexer 61. Matching circuit 52 is disposed on a path that connects switch 44 and duplexer 62, and matches the impedance of switch 44 and antenna 2 with the impedance of duplexer 62. Matching circuit 53 is disposed on a path that connects switch 44 and duplexer 63, and matches the impedance of switch 44 and antenna 2 with the impedance of duplexer 63.

Matching circuit 54 is disposed on a reception path that connects low noise amplifier 30 and switch 43, and matches the impedance of low noise amplifier 30 with the impedance of switch 43 and duplexers 61 to 63.

Switch 41 includes common terminals 41 a and 41 b, and selection terminals 41 c, 41 d, 41 e, and 41 f. Common terminal 41 a is connected to input terminal 115 of transmission amplifier circuit 10. Common terminal 41 b is connected to input terminal 125 of transmission amplifier circuit 20. Selection terminal 41 c is connected to transmission input terminal 111, selection terminal 41 d is connected to transmission input terminal 112, selection terminal 41 e is connected to transmission input terminal 121, and selection terminal 41 f is connected to transmission input terminal 122. Switch 41 is disposed on the input terminal side of transmission amplifier circuits 10 and 20. In the above-described connection configuration, switch 41 switches connection of transmission amplifier circuit 10 between transmission input terminal 111 and transmission input terminal 112, and switches connection of transmission amplifier circuit 20 between transmission input terminal 121 and transmission input terminal 122. Switch 41 is implemented as, for example, a double pole four throw (DP4T) switching circuit.

It should be noted that switch 41 may include: a single pole double throw (SPDT) switch which includes common terminal 41 a and selection terminals 41 c and 41 d; and an SPDT switch which includes common terminal 41 b and selection terminals 41 e and 41 f.

A transmission signal of communication band A, for example, is input through transmission input terminal 111, and a transmission signal of communication band B, for example, is input through transmission input terminal 112. A transmission signal of communication band C, for example, is input through transmission input terminals 121 and 122.

A transmission signal of communication band A or B in the fourth generation mobile communication system (4G), for example, may be input through transmission input terminal 111, and a transmission signal of communication band A or B in the fifth generation mobile communication system (5G), for example, may be input through transmission input terminal 112. A transmission signal of communication band C in 4G, for example, may be input through transmission input terminal 121, and a transmission signal of communication band C in 5G, for example, may be input through transmission input terminal 122.

It should be noted that switch 41 may be an SPDT switching circuit including: a common terminal that is connected to a transmission input terminal (referred to as a first transmission input terminal) out of transmission input terminals 111, 112, 121, and 122; one selection terminal that is connected to input terminal 115 of transmission amplifier circuit 10; and the other selection terminal that is connected to input terminal 125 of transmission amplifier circuit 20.

In this case, for example, a transmission signal of any one of communication band A, communication band B, and communication band C is selectively input through the first transmission input terminal, and switch 41 switches connection of the first transmission input terminal between transmission amplifier circuit 10 and transmission amplifier circuit 20 according to the transmission signal that has been input. In addition, for example, a transmission signal of 4G or a transmission signal of 5G may be input through the first transmission input terminal, and switch 41 may switch connection of the first transmission input terminal between transmission amplifier circuit 10 and transmission amplifier circuit 20 according to the transmission signal that has been input.

In addition, switch 41 may be implemented as a double pole double throw (DPDT) switching circuit that includes two common terminals and two selection terminals. In this case, the first transmission input terminal is connected to one of the common terminals, and the second transmission input terminal is connected to remaining one of the common terminals. In addition, one of the selection terminals is connected to transmission amplifier circuit 10, and remaining one of the selection terminals is connected to transmission amplifier circuit 20. In this connection configuration, switch 41 switches connection of the one of the common terminals between the one of the selection terminals and the remaining one of the selection terminals, and switches connection of the remaining one of the common terminals between the one of the selection terminals and the remaining one of the selection terminals.

In this case, for example, a transmission signal of communication band A or B is input through the first transmission input terminal, and a transmission signal of communication band C is input through the second transmission input terminal. In addition, for example, a transmission signal of 4G is input through the first transmission input terminal, and a transmission signal of 5G is input through the second transmission input terminal.

Switch 42 includes common terminals 42 a and 42 b, and selection terminals 42 c, 42 d, and 42 e. Common terminal 42 a is connected to output terminal 116 of transmission amplifier circuit 10, and common terminal 42 b is connected to output terminal 126 of transmission amplifier circuit 20. Selection terminal 42 c is connected to transmission filter 61T, selection terminal 42 d is connected to transmission filter 62T, and selection terminal 42 e is connected to transmission filter 63T. Switch 42 is disposed on the output terminal side of transmission amplifier circuits 10 and 20. In the above-described connection configuration, switch 42 switches connection of transmission amplifier circuit 10 between transmission filter 61T and transmission filter 62T, and connects and disconnects transmission amplifier circuit 20 and transmission filter 63T. Switch 42 is implemented as, for example, a double pole triple throw (DP3T) switching circuit.

It should be noted that switch 42 may include: a SPDT switch including common terminal 42 a and selection terminals 42 c and 42 d; and a single pole single throw (SPST) switch including common terminal 42 b and selection terminal 42 e.

Switch 43 includes common terminal 43 a and selection terminals 43 b, 43 c, and 43 d. Common terminal 43 a is connected to an input terminal of low noise amplifier 30 via matching circuit 54. Selection terminal 43 b is connected to reception filter 61R, selection terminal 43 c is connected to reception filter 62R, and selection terminal 43 d is connected to reception filter 63R. In the above-described connection configuration, switch 43 connects and disconnects low noise amplifier 30 and reception filter 61R, connects and disconnects low noise amplifier 30 and reception filter 62R, and connects and disconnects low noise amplifier 30 and reception filter 63R. Switch 43 is implemented as, for example, a single pole triple throw (SP3T) switching circuit.

Switch 44 is one example of an antenna switch, and connected to antenna connection terminal 100. Switch 44 switches connection of antenna connection terminal 100 between (1) transmission path AT and reception path AR, (2) transmission path BT and reception path BR, and (3) transmission path CT and reception path CR. It should be noted that switch 44 is implemented as a multiple-connection switching circuit capable of simultaneously performing the connection of antenna connection terminal 100 with two or more of the above-described (1) to (3).

It should be noted that the above-described transmission filters 61T to 63T and reception filters 61R to 63R may be each, for example, one of an acoustic wave filter using a surface acoustic wave (SAW), an acoustic wave filter using a bulk acoustic wave (BAW), an LC resonant filter, and a dielectric filter, but not limited to these filters.

It should be noted that matching circuits 51 to 54 are not indispensable components for the radio frequency module according to the present disclosure.

In addition, a matching circuit may be disposed between transmission amplifier circuit 10 and switch 42, and between transmission amplifier circuit 20 and switch 42. In addition, a diplexer, a coupler, or the like may be disposed between antenna connection terminal 100 and switch 44.

According to the configuration of radio frequency module 1, transmission amplifier circuit 10, switch 42, transmission filter 61T, matching circuit 51, and switch 44 are included in a first transmission circuit that transfers a transmission signal of communication band A to antenna connection terminal 100. Switch 44, matching circuit 51, reception filter 61R, switch 43, matching circuit 54, and low noise amplifier 30 are included in a first reception circuit that transfers a reception signal of communication band A that has been received from antenna 2 via antenna connection terminal 100.

In addition, transmission amplifier circuit 10, switch 42, transmission filter 62T, matching circuit 52, and switch 44 are included in a second transmission circuit that transfers a transmission signal of communication band B to antenna connection terminal 100. Switch 44, matching circuit 52, reception filter 62R, switch 43, matching circuit 54, and low noise amplifier 30 are included in a second reception circuit that transfers a reception signal of communication band B that has been received from antenna 2 via antenna connection terminal 100.

In addition, transmission amplifier circuit 20, switch 42, transmission filter 63T, matching circuit 53, and switch 44 are included in a third transmission circuit that transfers a transmission signal of communication band C to antenna connection terminal 100. Switch 44, matching circuit 53, reception filter 63R, switch 43, matching circuit 54, and low noise amplifier 30 are included in a third reception circuit that transfers a reception signal of communication band C that has been received from antenna 2 via antenna connection terminal 100.

According to the above-described circuit configuration, radio frequency module 1 is capable of at least one of transmitting, receiving, or transmitting and receiving a radio frequency signal of any one of communication band A, communication band B, and communication band C. Radio frequency module 1 is also capable of at least one of simultaneously transmitting, simultaneously receiving, or simultaneously transmitting and receiving a radio frequency signal of any one of communication band A, communication band B, and communication band C.

It should be noted that, the radio frequency module according to the present disclosure may be implemented without connecting the above-described three transmission circuits and the above-described three reception circuits to antenna connection terminal 100 via switch 44, and the above-described three transmission circuits and the above-described three reception circuits may be connected to antenna 2 via different terminals. It is sufficient if the radio frequency module according to the present disclosure includes PA control circuit 80, the first transmission circuit, and the third transmission circuit.

In addition, in the radio frequency module according to the present disclosure, it is sufficient if the first transmission circuit includes transmission amplifier circuit 10. In addition, it is sufficient if the third transmission circuit includes transmission amplifier circuit 20.

In addition, low noise amplifier 30 and at least one of switches 41 to 44 may be disposed in a single semiconductor IC. The semiconductor IC is configured by, for example, a CMOS. More specifically, the semiconductor IC is fabricated by SOI processing. This allows manufacturing the semiconductor IC at a low manufacturing cost. It should be noted that the semiconductor IC may include at least one of GaAs, SiGe, or GaN. With this, it is possible to output a radio frequency signal having a high-quality amplification performance and noise performance.

FIG. 2 is a diagram illustrating a circuit configuration of transmission amplifier circuit 10 according to the embodiment. As illustrated in the diagram, transmission amplifier circuit 10 includes: input terminal 115; output terminal 116; amplifying element 11 (a pre-stage amplifying element); amplifying element 12 (a first amplifying element); amplifying element 13 (a second amplifying element); interstage transformer 14 (a transformer); capacitor 16; and output transformer (balun: balanced-unbalanced transforming element) 15. Amplifying elements 11 to 13, interstage transformer 14, and capacitor 16 are included in power amplifier 10A. Power amplifier 10A is one example of a first power amplifier.

Interstage transformer 14 includes primary coil 14 a and secondary coil 14 b.

Amplifying element 11 includes an input terminal connected to input terminal 115, and an output terminal connected to an unbalanced terminal of interstage transformer 14. One of balanced terminals of interstage transformer 14 is connected to an input terminal of amplifying element 12, and a remaining one of the balanced terminals of interstage transformer 14 is connected to an input terminal of amplifying element 13.

A radio frequency signal input through input terminal 115 is amplified by amplifying element 11 in a state in which bias voltage Vcc1 is applied to amplifying element 11. The radio frequency signal that has been amplified is subjected to balanced-unbalanced transformation by interstage transformer 14. At this time, a non-inverted input signal is output from the one of the balanced terminals of interstage transformer 14, and an inverted input signal is output from the remaining one of the balanced terminals of interstage transformer 14.

Output transformer 15 is one example of a first output transformer, and includes primary coil (a first coil) 15 a and secondary coil (a second coil) 15 b. Primary coil 15 a has one end connected to an output terminal of amplifying element 12, and the other end connected to an output terminal of amplifying element 13. In addition, bias voltage Vcc2 is supplied to the midpoint of primary coil 15 a. Secondary coil 15 b has one end connected to output terminal 116, and the other end connected to the ground. In other words, output transformer 15 is connected between the output terminals of amplifying elements 12 and 13 and output terminal 116.

Capacitor 16 is connected between the output terminal of amplifying element 12 and the output terminal of amplifying element 13.

The non-inverted input signal amplified by amplifying element 12 and the inverted input signal amplified by amplifying element 13 are impedance transformed by output transformer 15 and capacitor 16 while being maintained in antiphase. In other words, the output impedance of power amplifier 10A at output terminal 116 is matched with the input impedance of switch 42 and transmission filters 61T and 62T illustrated in FIG. 1, by output transformer 15 and capacitor 16. It should be noted that the capacitive element connected between the ground and the path connecting output terminal 116 and secondary coil 15 b also contributes to the above-described impedance matching. The above-described capacitive element may be disposed in series on the path connecting output terminal 116 and secondary coil 15 b, or the above-described capacitive element need not necessarily be included.

Here, amplifying elements 11 to 13, interstage transformer 14, and capacitor 16 are included in power amplifier 10A. In particular, amplifying elements 11 to 13 and interstage transformer 14 are often integrally formed as one chip, or on the same board. In contrast, output transformer 15 requires a high Q-factor to handle a high-power transmission signal, and thus is not integrally formed with, for example, amplifying elements 11 to 13 and interstage transformer 14. In other words, among the circuit components included in transmission amplifier circuit 10, the circuit components other than output transformer 15 are included in power amplifier 10A.

It should be noted that amplifying element 11 and capacitor 16 need not necessarily be included in power amplifier 10A.

According to the circuit configuration of transmission amplifier circuit 10, amplifying elements 12 and 13 operate in antiphase. Here, fundamental-wave currents from amplifying elements 12 and amplifying element 13 flow in antiphase; that is, in opposite directions. Accordingly, a fundamental-wave current does not flow into a ground line or a power supply line located at a substantially equal distance from amplifying elements 12 and 13. In view of the above, the inflow of an unnecessary current to the above-described lines is negligible. It is thus possible to inhibit a decrease in power gain that is found in conventional transmission amplifier circuits. In addition, since the non-inverted signal and the inverted signal amplified by amplifying elements 12 and 13 are combined, noise components superimposed equally on both of the signals can be canceled, and thus it is possible to reduce spurious waves such as harmonic components.

It should be noted that amplifying element 11 is not an indispensable component for transmission amplifier circuit 10. An element that transforms unbalanced input signals to non-inverted input signals and inverted input signals is not limited to interstage transformer 14. Capacitor 16 is not an indispensable component for performing impedance matching.

In addition, although not illustrated in the diagrams, transmission amplifier circuit 20 has a circuit configuration equivalent to the circuit configuration of transmission amplifier circuit 10 illustrated in FIG. 2. More specifically, transmission amplifier circuit 20 includes: input terminal 125; output terminal 126; amplifying element 21 (a pre-stage amplifying element); amplifying element 22 (a third amplifying element); amplifying element 23 (a fourth amplifying element); interstage transformer (a transformer) 24; capacitor 26; and output transformer (balun: balanced-unbalanced transforming element) 25. Amplifying elements 21 to 23, interstage transformer 24, and capacitor 26 are included in power amplifier 20A. Power amplifier 20A is one example of a second power amplifier.

Interstage transformer 24 includes primary coil 24 a and secondary coil 24 b.

Amplifying element 21 includes an input terminal connected to input terminal 125, and an output terminal connected to an unbalanced terminal of interstage transformer 24. One of balanced terminals of interstage transformer 24 is connected to an input terminal of amplifying element 22, and a remaining one of the balanced terminals of interstage transformer 24 is connected to an input terminal of amplifying element 23.

Output transformer 25 is one example of a second output transformer, and includes primary coil (a third coil) 25 a and secondary coil (a fourth coil) 25 b. Primary coil 25 a has one end connected to an output terminal of amplifying element 22, and the other end connected to an output terminal of amplifying element 23. In addition, bias voltage Vcc2 is supplied to the midpoint of primary coil 25 a. Secondary coil 25 b has one end connected to output terminal 126, and the other end connected to the ground. In other words, output transformer 25 is connected between the output terminals of amplifying elements 22 and 23 and output terminal 126.

Capacitor 26 is connected between the output terminal of amplifying element 22 and the output terminal of amplifying element 23.

Here, amplifying elements 21 to 23, interstage transformer 24, and capacitor 26 are included in power amplifier 20A. In particular, amplifying elements 21 to 23 and interstage transformer 24 are often integrally formed as one chip, or on the same board. In contrast, output transformer 25 is not integrally formed with amplifying elements 21 to 23 and interstage transformer 24, for example.

It should be noted that amplifying element 21 and capacitor 26 need not necessarily be included in power amplifier 20A.

According to the circuit configuration of transmission amplifier circuit 20, it is possible to inhibit decrease in power gain that is found in conventional transmission amplifier circuits. In addition, since the non-inverted signal and the inverted signal amplified by amplifying elements 22 and 23 are combined, noise components superimposed equally on both of the signals can be canceled, and thus it is possible to reduce spurious waves such as harmonic components.

It should be noted that amplifying element 21 is not an indispensable component for transmission amplifier circuit 20. An element that transforms unbalanced input signals to non-inverted input signals and inverted input signals is not limited to interstage transformer 24. Capacitor 26 is not an indispensable component for performing impedance matching.

Amplifying elements 11 to 13 and 21 to 23 and low noise amplifier 30 include, for example, a field-effect transistor (FET), a hetero-junction bipolar transistor (HBT), etc. which include a Si complementary metal oxide semiconductor (CMOS) or GaAs as a material.

It should be noted that transmission amplifier circuit 10 need not necessarily include differential power amplifier 10A, and may be an amplifier that includes a so-called single-end amplifying element which receives an unbalanced signal and outputs an unbalanced signal. In addition, transmission amplifier circuit 20 need not necessarily include differential power amplifier 20A, and may be an amplifier that includes a so-called single-end amplifying element which receives an unbalanced signal and outputs an unbalanced signal.

Here, in radio frequency module 1, transmission amplifier circuit 10 amplifies transmission signals of communication bands A and B, and transmission amplifier circuit 20 amplifies transmission signals of communication band C. In other words, the amplification performance of each of transmission amplifier circuits 10 and 20 is optimized in a specific frequency band (communication band), and thus radio frequency module 1 need to include a plurality of transmission amplifier circuits that support the respective frequency bands (communication bands). In addition, under the condition that radio frequency module 1 is mounted on a single mounting board, since a large number of circuit elements (amplifying elements 11 to and 21 to 23, interstage transformers 14 and 24, output transformers 15 and 25, and capacitors 16 and 26) are included in transmission amplifier circuits 10 and 20, radio frequency module 1 increases in size.

Furthermore, if the circuit elements are highly-densely mounted in order to reduce the size of radio frequency module 1, high-power transmission signals output from output transformers 15 and 25 interfere with each other. As a result, there arises a problem of degradation of the signal quality of the transmission signals.

In view of the above, the following describes a configuration of radio frequency module 1 whose size is reduced while quality degradation of the transmission signals output from radio frequency module 1 is inhibited.

2. Arrangement Configuration of Circuit Elements of Radio Frequency Module 1A According to Working Example 1

FIG. 3A is a schematic diagram illustrating a plan view configuration of radio frequency module 1A according to Working Example 1. FIG. 3B is a schematic diagram illustrating a cross-sectional configuration of radio frequency module 1A according to Working Example 1. More specifically, FIG. 3B is a cross-sectional view taken along line IIIB-IIIB of FIG. 3A. It should be noted that (a) in FIG. 3A illustrates a layout of the circuit elements when, of principal surfaces 91 a and 91 b located on opposite sides of module board 91, principal surface 91 a is viewed from the z-axis positive side. Meanwhile, (b) in FIG. 3A illustrates a perspective view of the layout of the circuit elements when principal surface 91 b is viewed from the z-axis positive side. In FIG. 3A, output transformers 15 and 25 formed in module board 91 are indicated by broken lines.

Radio frequency module 1A according to Working Example 1 specifically illustrates the arrangement configuration of the respective circuit elements included in radio frequency module 1 according to the embodiment.

As illustrated in FIG. 3A and FIG. 3B, radio frequency module 1A according to the present working example further includes module board 91, resin components 92 and 93, and external-connection terminals 150 in addition to the circuit configuration illustrated in FIG. 1.

Module board 91 is a board which includes principal surface 91 a (a first principal surface) and principal surface 91 b (a second principal surface) on opposite sides thereof, and on which the above-described transmission circuit and the above-described reception circuit are mounted. As module board 91, for example, a low temperature co-fired ceramic (LTCC) board having a stacked structure including a plurality of dielectric layers, a high temperature co-fired ceramic (HTCC) board, a component built-in board, a board including a redistribution layer (RDL), or a printed board or the like is used.

Resin component 92 is disposed on principal surface 91 a of module board 91 and covers a portion of the above-described transmission circuit, a portion of the above-described reception circuit, and principal surface 91 a of module board 91. Resin component 92 has a function of ensuring reliability such as mechanical strength and moisture resistance of the circuit elements included in the above-described transmission circuit and the above-described reception circuit. Resin component 93 is disposed on principal surface 91 b of module board 91 and covers a portion of the above-described transmission circuit, a portion of the above-described reception circuit, and principal surface 91 b of module board 91. Resin component 93 has a function of ensuring reliability such as mechanical strength and moisture resistance of the circuit elements included in the above-described transmission circuit and the above-described reception circuit. It should be noted that resin components 92 and 93 are not indispensable components for the radio frequency module according to the present disclosure.

As illustrated in FIG. 3A and FIG. 3B, in radio frequency module 1A according to the present working example, power amplifiers 10A and 20A, duplexers 61, 62, and 63, and matching circuits 51, 52, 53, and 54 are disposed on principal surface 91 a (a first principal surface) of module board 91. PA control circuit 80, low noise amplifier 30, switches 41, 42, 43, and 44 are each one example of the first circuit components, and disposed on principal surface 91 b (a second principal surface) of module board 91. Output transformers 15 and 25 are provided inside module board 91.

In other words, according to the present working example, power amplifiers 10A and 20A are disposed on principal surface 91 a, and output transformers 15 and 25 are formed inside module board 91.

According to the above-described configuration, it is possible to reduce the size of radio frequency module 1A compared to the configuration in which power amplifiers 10A and 20A and output transformers 15 and 25 are all disposed on one surface of module board 91. Accordingly, it is possible to provide small-sized radio frequency module 1A that includes a differential power amplifier, and supports multi-band technologies.

It should be noted that, although not illustrated in FIG. 3A, lines included in transmission paths AT, BT, and CT, and reception paths AR, BR, and CR illustrated in FIG. 1 are provided inside module board 91 and on principal surfaces 91 a and 91 b. In addition, each of the above-described lines may be a bonding wire having ends bonded to principal surfaces 91 a and 91 b and any of the circuit elements included in radio frequency module 1A, or may be a terminal, an electrode, or a line disposed on a surface of any of the circuit elements included in radio frequency module 1A.

Power amplifier 10A is one example of a first power amplifier that amplifies a transmission signal of a first frequency band including communication bands A and B. Power amplifier 20A is one example of a second power amplifier that amplifies a transmission signal of a second frequency band including communication band C. According to the present working example, the first frequency band (communication bands A and B) is lower than the second frequency band (communication band C).

In addition, in radio frequency module 1A according to the present working example, in a plan view of module board 91, output transformer 15 is disposed in region 153 (a first region) adjacent to outer side 103 (a first outer side) among four outer sides 101, 102, 103, and 104 that define a first quadrilateral region in which power amplifier 10A is disposed, as illustrated in (a) in FIG. 3A. Output transformer 25 is disposed in region 254 (a second region) adjacent to outer side 204 (a second outer side) among four outer sides 201, 202, 203, and 204 that define a second quadrilateral region in which power amplifier 20A is disposed. Here, outer side 103 is, among the four outer sides 101, 102, 103, and 104, one of the sides other than outer side 101 that is closest to the second quadrilateral region in which power amplifier 20A is disposed. Outer side 204 is, among the four outer sides 201, 202, 203, and 204, one of the sides other than outer side 201 that is closest to the first quadrilateral region in which power amplifier 10A is disposed.

It should be noted that, in the configuration of radio frequency module 1A according to the present working example in which output transformer 15 is disposed in the first region adjacent to the first outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the first outer side and output transformer 15. In addition, in the configuration in which output transformer 25 is disposed in the second region adjacent to the second outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the second outer side and output transformer 25.

According to the above-described configuration of radio frequency module 1A according to the present working example, output transformer 15 that transfers a high-power transmission signal from power amplifier 10A is not disposed in the region adjacent to outer side 101 that is closest to power amplifier 20A. In addition, output transformer 25 that transfers a high-power transmission signal from power amplifier 20A is not disposed in the region adjacent to outer side 201 that is closest to power amplifier 10A. With this configuration, it is possible to avoid output transformer 15 and output transformer 25 from being put in a nearest-neighbor relationship. Accordingly, it is possible to inhibit high-power transmission signals output from power amplifiers 10A and 20A from interfering with each other. As a result, degradation of the signal quality of the transmission signals can be reduced.

In addition, power amplifier 10A includes at least amplifying elements 12 and 13, and power amplifier 20A includes at least amplifying elements 22 and 23. Accordingly, there are a large number of circuit elements. As a result, the mounting area of radio frequency module 1A tends to be large. In contrast, in radio frequency module 1A according to the present working example, power amplifiers 10A and 20A and the first circuit components such as PA control circuit 80, low noise amplifier 30, and switches 41, 42, 43, and 44 are disposed separately on principal surface 91 a and principal surface 91 b of module board 91. As a result, it is possible to further miniaturize radio frequency module 1A.

It should be noted that radio frequency module 1 according to the present disclosure is not limited to the arrangement relation of output transformers 15 and 25 in radio frequency module 1A according to Working Example 1.

FIG. 4A is a schematic diagram illustrating a plan view configuration on principal surface 91 a of radio frequency module 1C according to Variation 1. In the diagram, a layout of the circuit elements when, of principal surfaces 91 a and 91 b located on opposite sides of module board 91, principal surface 91 a is viewed from the z-axis positive side is illustrated. In addition, in the diagram, output transformers 15 and 25 formed in module board 91 are indicated by broken lines.

In radio frequency module 1C according to the present variation, in a plan view of module board 91, output transformer 15 is disposed in region 153 (a first region) adjacent to outer side 103 (a first outer side) among four outer sides 101, 102, 103, and 104 that define a first quadrilateral region in which power amplifier 10A is disposed, as illustrated in FIG. 4A. Output transformer 25 is disposed in region 253 (a second region) adjacent to outer side 203 (a second outer side) among four outer sides 201, 202, 203, and 204 that define a second quadrilateral region in which power amplifier 20A is disposed. Here, outer side 103 is, among the four outer sides 101, 102, 103, and 104, one of the sides other than outer side 101 that is closest to the second quadrilateral region in which power amplifier 20A is disposed. Outer side 203 is, among the four outer sides 201, 202, 203, and 204, one of the sides other than outer side 201 that is closest to the first quadrilateral region in which power amplifier 10A is disposed.

It should be noted that, in radio frequency module 1C according to Variation 1, in a plan view of module board 91, output transformer 15 may be disposed in region 154 (a first region) adjacent to outer side 104 (a first outer side) among the four outer sides 101, 102, 103, and 104 that define the first quadrilateral region in which power amplifier 10A is disposed.

According to the above-described configuration of radio frequency module 1C according to the present variation, output transformer 15 that transfers a high-power transmission signal from power amplifier 10A is not disposed in the region adjacent to outer side 101 that is closest to power amplifier 20A. In addition, output transformer 25 that transfers a high-power transmission signal from power amplifier 20A is not disposed in the region adjacent to outer side 201 that is closest to power amplifier 10A. With this configuration, it is possible to avoid output transformer 15 and output transformer 25 from being put in a nearest-neighbor relationship. Accordingly, it is possible to inhibit high-power transmission signals output from power amplifiers 10A and 20A from interfering with each other. As a result, degradation of the signal quality of the transmission signals can be reduced.

FIG. 4B is a schematic diagram illustrating a plan view configuration on principal surface 91 a of radio frequency module 1D according to Variation 2. In the diagram, a layout of the circuit elements when, of principal surfaces 91 a and 91 b located on opposite sides of module board 91, principal surface 91 a is viewed from the z-axis positive side is illustrated. In addition, in the diagram, output transformers 15 and 25 formed in module board 91 are indicated by broken lines.

In radio frequency module 1D according to the present variation, in a plan view of module board 91, output transformer 15 is disposed in region 156 (a fourth region) adjacent to outer side 104 (a first outer side) among four outer sides 101, 102, 103, and 104 that define a first quadrilateral region in which power amplifier 10A is disposed, as illustrated in FIG. 4B. Output transformer 25 is disposed in region 256 (a sixth region) adjacent to outer side 204 (a second outer side) among four outer sides 201, 202, 203, and 204 that define a second quadrilateral region in which power amplifier 20A is disposed. Here, outer side 104 is, among the four outer sides 101, 102, 103, and 104, one of sides other than outer side 101 that is closest to the second quadrilateral region in which power amplifier 20A is disposed. Outer side 204 is, among the four outer sides 201, 202, 203, and 204, one of sides other than outer side 201 that is closest to the first quadrilateral region in which power amplifier 10A is disposed. In addition, the first region adjacent to outer side 104 (the first outer side) among outer sides 101, 102, 103, and 104 includes region 155 (a third region) adjacent to outer side 104 (the first outer side) and region 156 (the fourth region) that is located further away from the second quadrilateral region than region 155. In addition, the second region adjacent to outer side 204 among outer sides 201, 202, 203, and 204 includes region 255 (a fifth region) adjacent to outer side 204 (the second outer side) and region 256 (the sixth region) that is located further away from the first quadrilateral region than region 255.

According to the above-described configuration of radio frequency module 1D according to the present variation, output transformer 15 is not disposed in the region adjacent to outer side 101 that is closest to power amplifier 20A, but disposed in, of the two regions adjacent to outer side 104, region 156 that is located further away from power amplifier 20A. Output transformer 25 is not disposed in the region adjacent to outer side 201 that is closest to power amplifier 10A, but disposed in, of the two regions adjacent to outer side 204, region 256 that is located further away from power amplifier 10A. With this configuration, it is possible to avoid output transformer 15 and output transformer 25 from being put in a nearest-neighbor relationship. Accordingly, it is possible to inhibit high-power transmission signals output from power amplifiers 10A and 20A from interfering with each other. As a result, degradation of the signal quality of the transmission signals can be reduced.

It should be noted that, in the configurations of radio frequency modules 1A and 1C in which output transformer 15 is disposed in the first region adjacent to the first outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the first outer side and output transformer 15. In addition, in the configuration in which output transformer 25 is disposed in the second region adjacent to the second outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the second outer side and output transformer 25.

In addition, in the configuration of radio frequency module 1D in which output transformer 15 is disposed in the fourth region adjacent to the first outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the first outer side and output transformer 15. In addition, in the configuration in which output transformer 25 is disposed in the sixth region adjacent to the second outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the second outer side and output transformer 25.

Returning again to FIG. 3A and FIG. 3B, in radio frequency module 1A according to the present working example, a plurality of external-connection terminals 150 are disposed on the principal surface 91 b (the second principal surface) side of module board 91. Radio frequency module 1A exchanges electrical signals with a motherboard disposed on the z-axis negative side of radio frequency module 1A via the plurality of external-connection terminals 150. As illustrated in (b) in FIG. 3A, the plurality of external-connection terminals include: antenna connection terminal 100; transmission input terminals 111, 112, 121, and 122; reception output terminal 130; and control signal terminal 140. In addition, one or more of the plurality of external-connection terminals 150 are set to ground potential of the motherboard. Of principal surfaces 91 a and 91 b, power amplifiers 10A and 20A which are difficult to reduce the height are not disposed on principal surface 91 b facing the motherboard, but low noise amplifier 30, PA control circuit 80, and switches 41 o 44 which are easy to reduce the height are disposed on principal surface 91 b. Accordingly, it is possible to reduce the height of radio frequency module 1A as a whole.

Power amplifiers 10A and 20A are components that generate a large amount of heat among the circuit components included in radio frequency module 1A. In order to improve the heat dissipation property of radio frequency module 1A, it is important to dissipate heat generated by power amplifiers 10A and 20A to the motherboard through a heat dissipation path having a small thermal resistance. If power amplifiers 10A and 20A are mounted on principal surface 91 b, the electrode lines connected to power amplifiers 10A and 20A are disposed on principal surface 91 b. For that reason, as the heat dissipation path, a heat dissipation path that passes though only a planar line pattern (along the xy plane direction) on principal surface 91 b is included. The above-described planar line pattern is formed using a metal thin film, and thus has a large thermal resistance. For that reason, when power amplifiers 10A and 20A are disposed on principal surface 91 b, the heat dissipation property is decreased.

In contrast, in the case where power amplifiers 10A and 20A are disposed on principal surface 91 a as in the present working example, it is possible to connect power amplifiers 10A and 20A to external-connection terminals 150 via penetrating electrodes that penetrates through module board 91 between principal surface 91 a and principal surface 91 b. As a result, it is possible to exclude a heat dissipation path that passes through only the planar line pattern along the xy plane direction which has a large thermal resistance, from among the lines in module board 91, as the heat dissipation paths for power amplifiers 10A and 20A. It is thus possible to provide radio frequency module 1A having an improved heat dissipation property for dissipating heat from power amplifiers 10A and 20A to the motherboard.

In addition, in radio frequency module 1A, power amplifier 10A and power amplifier 20A may be included in a single first semiconductor IC.

According to this configuration, it is possible to inhibit degradation of the signal quality of transmission signals, while reducing the size of the transmission amplifier circuit.

In addition, as illustrated in FIG. 3A, it is desirable that a footprint of PA control circuit 80 does not overlap a footprint of output transformer 15 or a footprint of output transformer 25 in radio frequency module 1A.

According to this configuration, PA control circuit 80 that inputs/outputs digital control signals and output transformers 15 and 25 are disposed with module board 91 interposed therebetween, and a sufficient distance is ensured between PA control circuit 80 and output transformers 15 and 25. As a result, it is possible to inhibit output transformers 15 and 25 from being affected by a digital noise. It is thus possible to reduce degradation of the signal quality of radio frequency signals output from output transformers 15 and 25.

In addition, as illustrated in FIG. 3A, it is desirable that a footprint of switch 42 does not overlap the footprint of output transformer 15 or the footprint of output transformer 25 in radio frequency module 1A.

According to this configuration, it is possible to inhibit transmission signals output from output transformers 15 and 25 from leaking to an unconnected transmission or reception path via the off-capacitance of switch 42. It is thus possible to reduce degradation of the signal quality of radio frequency signals output from output transformers 15 and 25.

In addition, as illustrated in FIG. 3A, it is desirable that a footprint of switch 41 does not overlap the footprint of output transformer 15 or the footprint of output transformer 25 in radio frequency module 1A.

According to this configuration, it is possible to inhibit transmission signals input through the transmission input terminal from leaking to an unconnected output transformer via the off-capacitance of switch 41. It is thus possible to reduce degradation of the signal quality of radio frequency signals output from output transformers 15 and 25.

As illustrated in FIG. 3A, PA control circuit 80, switch 41, and switch 42 may be included in a single semiconductor IC 70 in radio frequency module 1A.

According to this configuration, PA control circuit 80, switch 41, and switch 42 are located in proximity to one another, and thus it is possible to miniaturize radio frequency module 1A. Furthermore, since the control line that connects PA control circuit 80 and switch 41 and the control line that connects PA control circuit 80 and switch 42 can be shortened, it is possible to inhibit noise generation from the control lines.

In radio frequency module 1A according to the present working example, low noise amplifier 30 and switches 43 and 44 are included in a single semiconductor IC 75, and the single semiconductor IC 75 is disposed on principal surface 91 b.

According to this configuration, low noise amplifier 30, switch 43, and switch 44 disposed on the reception path are located in proximity to one another, and thus it is possible to miniaturize radio frequency module 1A.

It should be noted that semiconductor IC 75 may not include at least one of switch 43 or switch 44.

As illustrated in FIG. 3A, in a plan view of module board 91, it is desirable that footprints of output transformers 15 and 25 do not overlap a footprint of semiconductor IC 70.

According to this configuration, it is possible to: inhibit output transformers 15 and 25 from being affected by a digital noise; inhibit transmission signals output from output transformers 15 and 25 from leaking to an unconnected transmission or reception path via the off-capacitance of switch 42; or inhibit transmission signals input through the transmission input terminal from leaking to an unconnected output transformer via the off-capacitance of switch 41. It is thus possible to reduce degradation of the signal quality of radio frequency signals output from output transformers 15 and 25.

In radio frequency module 1A according to the present working example, power amplifiers 10A and 20A are disposed on principal surface 91 a, and low noise amplifier 30 is disposed on principal surface 91 b. According to this configuration, power amplifiers 10A and 20A that amplify transmission signals and low noise amplifier 30 that amplifies reception signals are separately disposed on different sides of module board 91, and thus it is possible to improve isolation between a transmission side and a reception side.

As illustrated in FIG. 3A and FIG. 3B, in a plan view of module board 91, external-connection terminals 150 set to ground potential are disposed between low noise amplifier 30 and output transformers 15 and 25.

According to this configuration, the plurality of external-connection terminals 150 which are applied as ground electrodes are disposed between low noise amplifier 30 that significantly affects the reception sensitivity of the reception circuit and output transformers 15 and 25 that transfer high-power transmission signals. Accordingly, it is possible to inhibit degradation of reception sensitivity due to an inflow of a transmission signal and harmonic of the transmission signal to the reception path.

It should be noted that, although duplexers 61 to 63 and matching circuits 51 to 54 are mounted on principal surface 91 a (the first principal surface), duplexers 61 to 63 and matching circuits 51 to 54 may be mounted on principal surface 91 b (the second principal surface). In addition, although low noise amplifier 30, PA control circuit 80, and switches 41 to 44 are mounted on principal surface 91 b (the second principal surface), low noise amplifier 30, PA control circuit 80, and switches 41 to 44 may be mounted on principal surface 91 a (the first principal surface).

It is desirable that module board 91 have a multilayer structure in which a plurality of dielectric layers are laminated, and that a ground electrode pattern be formed in at least one of the plurality of dielectric layers. According to this configuration, the electromagnetic field shielding function of module board 91 is improved.

In addition, output transformers 15 and 25 are provided inside module board 91 in radio frequency module 1A according to the present working example. In this case, the inductors included in output transformers 15 and 25 are planar coils implemented by electric conduction patterns of module board 91, for example. In such arrangement configuration of output transformers 15 and 25, it is desirable that footprints of power amplifiers 10A and 20A each do not overlap the footprint of output transformer 15 or the footprint of output transformer 25 in a plan view of module board 91.

Output transformers 15 and 25 each require a high Q-factor to handle a high-power transmission signal. Accordingly, it is desirable to avoid a change in magnetic fields formed by output transformers 15 and 25 due to power amplifiers 10A and 20A being located in proximity to output transformers 15 and 25. Power amplifiers 10A and 20A are not disposed in the above-described region where the footprints of power amplifiers 10A and 20A overlap the footprints of output transformers 15 and 25, and thus it is possible to maintain a high Q-factor of each of the inductors included in output transformers 15 and 25.

In radio frequency module 1A according to the present working example, it is desirable that circuit components be not disposed in a region on principal surface 91 a and principal surface 91 b where circuit components overlap the footprints of output transformers 15 and 25 in a plan view of module board 91.

Output transformers 15 and 25 each require a high Q-factor to handle a high-power transmission signal. Accordingly, it is desirable to avoid a change in magnetic fields formed by output transformers 15 and 25 due to the other circuit components being located in proximity to output transformers 15 and 25. Since no circuit component is disposed in the above-described region, it is possible to maintain a high Q-factor of each of the inductors included in output transformers 15 and 25.

Formation regions of output transformers 15 and 25 in which output transformers 15 and 25 are formed are defined as follows. The following describes a formation region of output transformer 15. Since a formation region of output transformer 25 is defined similarly to the definition of the formation region of output transformer 15, the following description omits the definition of the formation region of output transformer 25.

The formation region of output transformer 15 is a minimum region that includes a formation region in which primary coil 15 a is formed and a formation region in which secondary coil 15 b is formed, in a plan view of module board 91.

Here, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a and located at a first distance, which is substantially constant, from primary coil 15 a. In this case, a second distance that is a distance from each end of the line conductor to primary coil 15 a is greater than the first distance. An end and another end of secondary coil 15 b are points at which the distance from the line conductor to primary coil 15 a starts to change. Primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b and located at a first distance, which is substantially constant, from secondary coil 15 b. In this case, a second distance that is a distance from each end of the line conductor to secondary coil 15 b is greater than the first distance. An end and another end of primary coil 15 a are points at which the distance from the line conductor to secondary coil 15 b starts to change.

Alternatively, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a and having a first line width that is substantially constant. Primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b and having a first line width that is substantially constant.

Alternatively, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a and having a first film thickness that is substantially constant. Primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b and having a first film thickness that is substantially constant.

Alternatively, secondary coil 15 b is defined as a line conductor disposed along primary coil 15 a and having a first degree of coupling with primary coil 15 a that is substantially constant. Primary coil 15 a is defined as a line conductor disposed along secondary coil 15 b and having a first degree of coupling with secondary coil 15 b that is substantially constant.

It should be noted that external-connection terminals 150 may be columnar electrodes that penetrate through resin component 93 in the z-axis direction as illustrated in FIG. 3A and FIG. 3B, or may be bump electrodes 160 formed on principal surface 91 b as in radio frequency module 1B according to Variation 3 as illustrated in FIG. 5. In this case, resin component 93 need not be provided on principal surface 91 b.

In radio frequency module 1A according to Working Example 1 and radio frequency modules 1C and 1D according to Variations 1 and 2, external-connection terminals 150 may be disposed on principal surface 91 a. In addition, in radio frequency module 1B according to Variation 3, bump electrodes 160 may be disposed on principal surface 91 a.

3. Arrangement Configuration of Circuit Elements of Radio Frequency Module 1E According to Working Example 2

FIG. 6A is a schematic diagram illustrating a plan view configuration of radio frequency module 1E according to Working Example 2. FIG. 6B is a schematic diagram illustrating a cross-sectional configuration of radio frequency module 1E according to Variation 2. More specifically, FIG. 6B is a cross-sectional view taken along line VIB-VIB of FIG. 6A. It should be noted that (a) in FIG. 6A illustrates a layout of the circuit elements when, of principal surfaces 91 a and 91 b located on opposite sides of module board 91, principal surface 91 a is viewed from the z-axis positive side. Meanwhile, (b) in FIG. 6A illustrates a perspective view of the layout of the circuit elements when principal surface 91 b is viewed from the z-axis positive side.

Radio frequency module 1E according to Working Example 2 shows a specific arrangement of circuit elements included in radio frequency module 1 according to the embodiment. Radio frequency module 1E is different from radio frequency module 1A according to Working Example 1 in the arrangement of output transformers 15 and 25. Hereinafter, radio frequency module 1E according to Working Example 2 will be described. In the description, the same points as those of radio frequency module 1A according to Working Example 1 will be omitted, and different points will be mainly described.

As illustrated in FIG. 6A and FIG. 6B, in radio frequency module 1E according to the present working example, power amplifiers 10A and 20A, duplexers 61, 62, and 63, and matching circuits 51, 52, 53, and 54 are disposed on principal surface 91 a (a first principal surface) of module board 91. PA control circuit 80, output transformers 15 and 25, low noise amplifier 30, switches 41, 42, 43, and 44 are disposed on principal surface 91 b (a second principal surface) of module board 91. PA control circuit 80, low noise amplifier 30, and switches 41, 42, 43, and 44 are each one example of a first circuit component.

In other words, according to the present working example, power amplifiers 10A and 20A are disposed on principal surface 91 a, and output transformers 15 and 25 are disposed on principal surface 91 b.

According to the above-described configuration, it is possible to reduce the size of radio frequency module 1E compared to the configuration in which power amplifiers 10A and 20A and output transformers 15 and 25 are all disposed on one surface of module board 91. Accordingly, it is possible to provide small-sized radio frequency module 1E that includes a differential power amplifier, and supports multi-band technologies.

Output transformers 15 and 25 are, for example, surface mount chip elements each including a plurality of inductors. Furthermore, output transformers 15 and 25 may be, for example, integrated passive devices (IPDs) in each of which passive elements such as an inductor and the like are mounted inside of or on the surface of a Si substrate in an integrated manner. When output transformers 15 and 25 are IPDs, miniaturization of radio frequency module 1E can be facilitated.

In addition, in radio frequency module 1E according to the present working example, in a plan view of module board 91, output transformer 15 is disposed in region 153 (a first region) adjacent to outer side 103 (a first outer side) among four outer sides 101, 102, 103, and 104 that define a first quadrilateral region in which power amplifier 10A is disposed, as illustrated in (a) in FIG. 6A. Output transformer 25 is disposed in region 254 (a second region) adjacent to outer side 204 (a second outer side) among four outer sides 201, 202, 203, and 204 that define a second quadrilateral region in which power amplifier 20A is disposed. Here, outer side 103 is, among the four outer sides 101, 102, 103, and 104, one of sides other than outer side 101 that is closest to the second quadrilateral region in which power amplifier 20A is disposed. Outer side 204 is, among the four outer sides 201, 202, 203, and 204, one of sides other than outer side 201 that is closest to the first quadrilateral region in which power amplifier 10A is disposed.

According to the above-described configuration of radio frequency module 1E according to the present working example, output transformer 15 that transfers a high-power transmission signal from power amplifier 10A is not disposed in the region adjacent to outer side 101 that is closest to power amplifier 20A. In addition, output transformer 25 that transfers a high-power transmission signal from power amplifier 20A is not disposed in the region adjacent to outer side 201 that is closest to power amplifier 10A. According to this configuration, it is possible to avoid output transformer 15 and output transformer 25 from being put in a nearest-neighbor relationship. Accordingly, it is possible to inhibit high-power transmission signals output from power amplifiers 10A and 20A from interfering with each other. As a result, degradation of the signal quality of the transmission signals can be reduced.

It should be noted that, in the configuration of radio frequency module 1E in which output transformer 15 is disposed in the first region adjacent to the first outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the first outer side and output transformer 15. In addition, in the configuration in which output transformer 25 is disposed in the second region adjacent to the second outer side, in a plan view of module board 91, another circuit element or circuit component may be disposed between the second outer side and output transformer 25.

It should be noted that radio frequency module 1 according to the present disclosure is not limited to the arrangement relation of output transformers 15 and 25 in radio frequency module 1E according to Working Example 2. Output transformers 15 and 25 may be in the arrangement relation illustrated in FIG. 4A and FIG. 4B, and may be disposed on principal surface 91 b instead of being formed inside module board 91.

In radio frequency module 1E according to the present working example, output transformers 15 and 25 are disposed on principal surface 91 b. However, it is desirable that the footprints of power amplifiers 10A and 20A each do not overlap the footprint of output transformer 15 or the footprint of output transformer 25 in a plan view of module board 91.

Output transformers 15 and 25 each require a high Q-factor to handle a high-power transmission signal. Accordingly, it is desirable to avoid a change in magnetic fields formed by output transformers 15 and 25 due to power amplifiers 10A and 20A being located in proximity to output transformers 15 and 25. Power amplifiers 10A and 20A are not disposed in the above-described region where power amplifiers 10A and 20A overlap output transformers 15 and 25, and thus it is possible to maintain a high Q-factor of each of the inductors included in output transformers 15 and 25.

In radio frequency module 1E according to the present working example, it is desirable that circuit components be not disposed in a region on principal surface 91 b and a region inside module board 91 where circuit components overlap output transformers 15 and 25 in a plan view of module board 91.

Output transformers 15 and 25 each require a high Q-factor to handle a high-power transmission signal. Accordingly, it is desirable to avoid a change in magnetic fields formed by output transformers 15 and 25 due to the other circuit components being located in proximity to output transformers 15 and 25. Since no circuit component is disposed in the above-described regions, it is possible to maintain a high Q-factor of each of the inductors included in output transformers 15 and 25.

3. Advantageous Effects, Etc.

As described above, radio frequency module 1 according to the embodiment includes module board 91 including principal surface 91 a and principal surface 91 b on opposite sides of module board 91; power amplifier 10A configured to amplify a transmission signal of a first frequency band; power amplifier 20A configured to amplify a transmission signal of a second frequency band different from the first frequency band; output transformer 15 including primary coil 15 a and secondary coil 15 b; and output transformer 25 including primary coil 25 a and secondary coil 25 b. In radio frequency module 1, power amplifier 10A includes amplifying element 12 and amplifying element 13, power amplifier 20A includes amplifying element 22 and amplifying element 23, one of ends of primary coil 15 a is connected to an output terminal of amplifying element 12, and a remaining one of the ends of primary coil 15 a is connected to an output terminal of amplifying element 13, one of ends of primary coil 25 a is connected to an output terminal of amplifying element 22, and a remaining one of the ends of primary coil 25 a is connected to an output terminal of amplifying element 23, power amplifier 10A and power amplifier 20A are disposed on principal surface 91 a, and output transformer 15 and output transformer 25 are disposed inside module board 91 or on principal surface 91 b.

According to this configuration, it is possible to reduce the size of radio frequency module 1 compared to the configuration in which power amplifiers 10A and 20A and output transformers 15 and 25 are all disposed on one surface of module board 91. Accordingly, it is possible to provide small-sized radio frequency module 1 that includes a differential power amplifier, and supports multi-band technologies.

In addition, in radio frequency module 1, in a plan view of module board 91, output transformer 15 may be disposed in a first region adjacent to a first outer side of four outer sides 101 to 104 defining a first quadrilateral region in which power amplifier 10A is disposed, and output transformer 25 may be disposed in a second region adjacent to a second outer side of four outer sides 201 to 204 defining a second quadrilateral region in which power amplifier 20A is disposed. The first outer side is other than outer side 101 located closest to the second quadrilateral region among the four outer sides 101 to 104 defining the first quadrilateral region. The second outer side is other than outer side 201 located closest to the first quadrilateral region among the four outer sides 201 to 204 defining the second quadrilateral region.

According to this configuration, output transformer 15 that transfers a high-power transmission signal from power amplifier 10A is not disposed in the region adjacent to outer side 101 that is closest to power amplifier 20A. In addition, output transformer 25 that transfers a high-power transmission signal from power amplifier 20A is not disposed in the region adjacent to outer side 201 that is closest to power amplifier 10A. According to this configuration, it is possible to avoid output transformer 15 and output transformer 25 from being put in a nearest-neighbor relationship. Accordingly, it is possible to inhibit high-power transmission signals output from power amplifiers 10A and 20A from interfering with each other. As a result, degradation of the signal quality of the transmission signals can be reduced.

In addition, in radio frequency module 1D, the first region may include a third region and a fourth region. The fourth region is located further away from the second quadrilateral region than the third region. The second region may include a fifth region and a sixth region. The sixth region is located further away from the first quadrilateral region than the fifth region. In a plan view of module board 91, output transformer 15 may be disposed in the fourth region included in the first region, and output transformer 25 may be disposed in the sixth region included in the second region.

According to this configuration, output transformer 15 is not disposed in the region adjacent to outer side 101 that is closest to power amplifier 20A, but disposed in, of the two regions included in the first region, the fourth region that is located further away from power amplifier 20A. In addition, output transformer 25 is not disposed in the region adjacent to outer side 201 that is closest to power amplifier 10A, but disposed in, of the two regions included in the second region, the sixth region that is located further away from power amplifier 10A. According to this configuration, it is possible to avoid output transformer 15 and output transformer 25 from being put in a nearest-neighbor relationship. Accordingly, it is possible to inhibit high-power transmission signals output from power amplifiers 10A and 20A from interfering with each other. As a result, degradation of the signal quality of the transmission signals can be reduced.

In addition, radio frequency module 1 may further include a plurality of external-connection terminals 150 disposed on principal surface 91 b.

According to this configuration, since power amplifiers 10A and 20A which are difficult to reduce the height are not disposed, of principal surfaces 91 a and 90 b, on principal surface 91 b facing the motherboard, it is possible to reduce the height of radio frequency module 1 as a whole.

In addition, in radio frequency module 1, power amplifier 10A and power amplifier 20A may be included in a single first semiconductor integrated circuit (IC).

According to this configuration, it is possible to inhibit degradation of the signal quality of transmission signals, while reducing the size of the transmission amplifier circuit.

In addition, radio frequency module 1 may further include PA control circuit 80 configured to control power amplifier 10A and power amplifier 20A. In radio frequency module 1, PA control circuit 80 may be disposed on principal surface 91 b, output transformer 15 and output transformer 25 may be disposed inside module board 91, and in a plan view of module board 91, the footprint of PA control circuit 80 may not overlap the footprint of output transformer 15 or the footprint of output transformer 25.

In addition, radio frequency module 1 may further include switch 41 connected to an input terminal of power amplifier 10A and an input terminal of power amplifier 20A, and in a plan view of module board 91, the footprint of switch 41 may not overlap the footprint of output transformer 15 or the footprint of output transformer 25.

According to this configuration, it is possible to inhibit transmission signals input through the transmission input terminal from leaking to an unconnected output transformer via the off-capacitance of switch 41. It is thus possible to reduce degradation of the signal quality of radio frequency signals output from output transformers 15 and 25.

In addition, radio frequency module 1 may further include switch 42 connected to the output terminal of power amplifier 10A and the output terminal of power amplifier 20A, and in a plan view of module board 91, the footprint of switch 42 may not overlap the footprint of output transformer 15 or the footprint of output transformer 25.

According to this configuration, it is possible to inhibit transmission signals output from output transformers 15 and 25 from leaking to an unconnected transmission or reception path via off-capacitance of switch 42. It is thus possible to reduce degradation of the signal quality of radio frequency signals output from output transformers 15 and 25.

In addition, in radio frequency module 1, PA control circuit 80, switch 42, and switch 41 may be included in a single semiconductor integrated circuit (IC).

According to this configuration, PA control circuit 80, switch 41, and switch 42 are located in proximity to one another, and thus it is possible to miniaturize radio frequency module 1. Furthermore, since the control line that connects PA control circuit 80 and switch 41 and the control line that connects PA control circuit 80 and switch 42 can be shortened, it is possible to inhibit noise generation from the control lines.

In addition, in radio frequency module 1A, output transformer 15 and output transformer 25 may be disposed inside module board 91, and in a plan view of module board 91, the footprint of semiconductor IC 70 may not overlap the footprint of output transformer 15 or the footprint of output transformer 25.

According to this configuration, it is possible to: inhibit output transformers 15 and 25 from being affected by a digital noise; inhibit transmission signals output from output transformers 15 and 25 from leaking to an unconnected transmission or reception path via the off-capacitance of switch 42; or inhibit transmission signals input through the transmission input terminal from leaking to an unconnected output transformer via the off-capacitance of switch 41. It is thus possible to reduce degradation of the signal quality of radio frequency signals output from output transformers 15 and 25.

In addition, radio frequency module 1 may further include low noise amplifier 30 disposed on principal surface 91 b, and in a plan view of module board 91, external-connection terminal 150 set to ground potential may be disposed between low noise amplifier 30 and output transformer 15 and between low noise amplifier 30 and output transformer 25.

According to this configuration, the plurality of external-connection terminals 150 which are applied as ground electrodes are disposed between low noise amplifier 30 that significantly affects the reception sensitivity of the reception circuit and output transformers 15 and 25 that transfer high-power transmission signals. Accordingly, it is possible to inhibit degradation of reception sensitivity due to an inflow of a transmission signal and harmonic of the transmission signal to the reception path.

In addition, communication device 5 includes: antenna 2; and RFIC 3 configured to process radio frequency signals transmitted and received by antenna 2; and radio frequency module 1 configured to transfer the radio frequency signals between antenna 2 and RFIC 3.

According to this configuration, it is possible to provide communication device 5 that includes a differential power amplifier, achieves reduction of quality degradation in transmission signals, and supports multi-band technologies.

Other Embodiments, Etc.

Although the radio frequency module and the communication device according to the embodiment of the present disclosure have been described above based on the embodiment, the working examples, and the variations, the radio frequency module and the communication device according to the present disclosure are not limited to the foregoing embodiment, working examples, and variations. The present disclosure also encompasses: other embodiments achieved by combining arbitrary structural components in the above-described embodiment, working examples, and variations; variations resulting from various modifications to the above-described embodiment, working examples, and variations that may be conceived by those skilled in the art without departing from the essence of the present disclosure; and various devices that include the above-described radio frequency module and the communication device.

For example, in the radio frequency module and the communication device according to the foregoing embodiment, working examples, and the variations, another circuit element and line, for example, may be inserted in a path connecting circuit elements and a signal path which are disclosed in the drawings.

Although only some exemplary embodiments of the present disclosure have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present disclosure. Accordingly, all such modifications are intended to be included within the scope of the present disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure is applicable widely to communication apparatuses such as mobile phones as a radio frequency module disposed in a multiband-compatible front-end unit. 

1: A radio frequency module, comprising: a module board including a first principal surface and a second principal surface on opposite sides of the module board; a first power amplifier disposed on the first principal surface and configured to amplify a transmission signal of a first frequency band; a second power amplifier disposed on the first principal surface and configured to amplify a transmission signal of a second frequency band different from the first frequency band; a first output transformer disposed inside the module board or on the second principal surface and including a first coil and a second coil; and a second output transformer disposed inside the module board or on the second principal surface and including a third coil and a fourth coil, wherein the first power amplifier includes a first amplifying element and a second amplifying element, the second power amplifier includes a third amplifying element and a fourth amplifying element, a first end of the first coil is connected to an output terminal of the first amplifying element, and a second end of the first coil is connected to an output terminal of the second amplifying element, and a first end of the third coil is connected to an output terminal of the third amplifying element, and a second end of the third coil is connected to an output terminal of the fourth amplifying element. 2: The radio frequency module of claim 1, wherein in a plan view of the module board, the first output transformer is disposed in a first region adjacent to a first outer side of four outer sides defining a first quadrilateral region in which the first power amplifier is disposed. 3: The radio frequency module of claim 2, wherein in a plan view of the module board, the second output transformer is disposed in a second region adjacent to a second outer side of four outer sides defining a second quadrilateral region in which the second power amplifier is disposed, the first outer side being other than an outer side located closest to the second quadrilateral region among the four outer sides defining the first quadrilateral region, the second outer side being other than an outer side located closest to the first quadrilateral region among the four outer sides defining the second quadrilateral region. 4: The radio frequency module of claim 3, wherein the first region includes a third region and a fourth region, the fourth region being located further away from the second quadrilateral region than the third region, the second region includes a fifth region and a sixth region, the sixth region being located further away from the first quadrilateral region than the fifth region, and in a plan view of the module board, the first output transformer is disposed in the fourth region included in the first region, and the second output transformer is disposed in the sixth region included in the second region. 5: The radio frequency module of claim 1, further comprising: a plurality of external-connection terminals disposed on the second principal surface. 6: The radio frequency module of claim 1, wherein the first power amplifier and the second power amplifier are included in a single semiconductor integrated circuit (IC). 7: The radio frequency module of claim 1, further comprising: a control circuit disposed on the second principal surface and configured to control the first power amplifier and the second power amplifier. 8: The radio frequency module of claim 7, wherein the first output transformer and the second output transformer are disposed inside the module board. 9: The radio frequency module of claim 8, wherein in a plan view of the module board, a footprint of the control circuit does not overlap a footprint of the first output transformer or a footprint of the second output transformer. 10: The radio frequency module of claim 1, further comprising: a switch disposed on the second principal surface and connected to the output terminal of the first power amplifier and the output terminal of the second power amplifier. 11: The radio frequency module of claim 10, wherein the first output transformer and the second output transformer are disposed inside the module board. 12: The radio frequency module of claim 11, wherein in a plan view of the module board, a footprint of the switch does not overlap a footprint of the first output transformer or a footprint of the second output transformer. 13: The radio frequency module of claim 1, further comprising: a switch disposed on the second principal surface and connected to an input terminal of the first power amplifier and an input terminal of the second power amplifier. 14: The radio frequency module of claim 13, wherein the first output transformer and the second output transformer are disposed inside the module board. 15: The radio frequency module of claim 14, and in a plan view of the module board, a footprint of the switch does not overlap a footprint of the first output transformer or a footprint of the second output transformer. 16: The radio frequency module of claim 1, further comprising: a control circuit configured to control the first power amplifier and the second power amplifier; a first switch connected to the output terminal of the first power amplifier and the output terminal of the second power amplifier; and a second switch connected to an input terminal of the first power amplifier and an input terminal of the second power amplifier, wherein the control circuit, the first switch, and the second switch are included in a single second semiconductor integrated circuit (IC) disposed on the second principal surface. 17: The radio frequency module of claim 16, wherein the first output transformer and the second output transformer are disposed inside the module board, and in a plan view of the module board, a footprint of the second semiconductor IC does not overlap a footprint of the first output transformer or a footprint of the second output transformer. 18: The radio frequency module of claim 1, further comprising: a low noise amplifier disposed on the second principal surface and configured to amplify a reception signal, wherein in a plan view of the module board, an external-connection terminal set to ground potential is disposed between the low noise amplifier and the first output transformer and between the low noise amplifier and the second output transformer. 19: A communication device, comprising: an antenna; a radio frequency (RF) signal processing circuit configured to process radio frequency signals transmitted and received by the antenna; and a radio frequency module configured to transfer the radio frequency signals between the antenna and the RF signal processing circuit, wherein the radio frequency module includes a module board including a first principal surface and a second principal surface on opposite sides of the module board; a first power amplifier disposed on the first principal surface and configured to amplify a transmission signal of a first frequency band; a second power amplifier disposed on the first principal surface and configured to amplify a transmission signal of a second frequency band different from the first frequency band; a first output transformer disposed inside the module board or on the second principal surface and including a first coil and a second coil; and a second output transformer disposed inside the module board or on the second principal surface and including a third coil and a fourth coil, wherein the first power amplifier includes a first amplifying element and a second amplifying element, the second power amplifier includes a third amplifying element and a fourth amplifying element, a first end of the first coil is connected to an output terminal of the first amplifying element, a second end of the first coil is connected to an output terminal of the second amplifying element, and a first of the second coil is connected to an output terminal of the first power amplifier, and a first end of the third coil is connected to an output terminal of the third amplifying element, a second end of the third coil is connected to an output terminal of the fourth amplifying element, and a first end of the fourth coil is connected to an output terminal of the second power amplifier. 20: A radio frequency module comprising: a module board including a first principal surface and a second principal surface on opposite sides of the module board; a first power amplifier disposed on the first principal surface; a second power amplifier disposed on the first principal surface; a first output transformer disposed inside the module board or on the second principal surface and connected to the first power amplifier; and a second output transformer disposed inside the module board or on the second principal surface and connected to the second power amplifier. 